Frozen pollack roe, which is an ingredient of salted cod roe and seasoned cod roe, is an ovary of pollack roe. Pollack is mainly caught at Northern fishing grounds around Alaska, U.S. and the Kamchatka, Russia, and in any case they are freezing-processed at onshore factories in isolated islands or on board. Conventionally frozen pollack roe is manufactured as in the following (1) to (4), for example:
(1) caught pollack is loaded one by one on a tray for automatic processor;
(2) the head of a pollack is cut by the automatic processor, and roe as well as offal are taken out with a roe scraping device:
(3) the roe scraped out with the offal is manually separated from the offal by an operator, for example;
(4) the roe separated from the offal is classified manually one by one in accordance with their shapes, colors, maturity and weight; and
(5) the classified roe of specified weight is frozen and packed as a product.
In the above step (4), the classification is performed on the basis of the following selection criteria (a) to (d):
(a) shapes: integrity or cut;
(b) colors: light color, dark color, brownish burnt or a bile adhered state;
(c) maturity: premature, mature or post-mature; and
(d) weight: after the selection based on (a) to (c), selected by weight.
In the determination of the above (c) for maturity, operators touch the roe with their hands to check the feel of the roe or visually determine the state of eggs of the pollack roe. Pollack roe is caught between January and April, and premature to mature pollack roe is caught in January and February, and mature to post-mature pollack roe is caught in March and April. Maturity of pollack roe varies with each fish, which is one of important elements for classification.
Patent Document 1 discloses a technique for a fish body treatment device to take roe or the like out from a fish body.    Patent Document 1: JP Patent Application Publication No. 2006-197893 A